HiFiNutNut said:
True about the nulls to the sides causing less radiated sound compared to omni (not box speakers), but I think OB's strength comes from the evenness of their radiation in terms of frequency, particularly when they have rear tweeters - their sound power will be smoother. Where the reflections come from is important, but more important to a "feeling of space" or listener envelopment, may be stronger decorrelation of reflection, those not coming from the first reflection points. Toole make a strong argument (supported by data) that absorbing first reflections reduces later decorrelated reflections, reducing the sense of spaciousness.
Rudolf said:
True, but probably easier said than done..
Rudolf said:
If you could see Figure 20.2, you'd see that above 5k, the sound power drops below the direct level - which I think would make it impossible to achieve by just moving seating. But yes, if we had a loudspeaker with true constant directivity above the room's transition frequency (say about 200hz), than changing listening distance would do it...
you are talking WHY
Who does know how do they sound ?
I do have a friend
He owns them build from a kit from
the master himself with the x-over
compared to my Quad 67 wit H sub-woofer
the sound great and even a bit more open.
Yes they do have some magic for sure
an a lot of fun
compared to the unities, totally different
but
in some sense same detail
sound-stage, ambiance and all
well to use a silly image
Quads and Orions are candlelight speakers
a Unity is a big sound
Three mangers are dead clean, a bit dead and not alive,
I do know them all, audiophile is not
my cup of tea, an feelling is all about,
as I do not know if may May piano is audiophile,
but fantastic id like very much
almost only 5 meters from my bed LOL
well music, photo, fashion, sewing, drawing design is my
center of life,
reading with candlelight too.
call it psychoacoustics, play with them
and if the image is what yoo are dreaming off
it is OK for you a long
as it drives you not mad.
than start again.
That is the reason the forum exists.
enjoy
Who does know how do they sound ?
I do have a friend
He owns them build from a kit from
the master himself with the x-over
compared to my Quad 67 wit H sub-woofer
the sound great and even a bit more open.
Yes they do have some magic for sure
an a lot of fun
compared to the unities, totally different
but
in some sense same detail
sound-stage, ambiance and all
well to use a silly image
Quads and Orions are candlelight speakers
a Unity is a big sound
Three mangers are dead clean, a bit dead and not alive,
I do know them all, audiophile is not
my cup of tea, an feelling is all about,
as I do not know if may May piano is audiophile,
but fantastic id like very much
almost only 5 meters from my bed LOL
well music, photo, fashion, sewing, drawing design is my
center of life,
reading with candlelight too.
call it psychoacoustics, play with them
and if the image is what yoo are dreaming off
it is OK for you a long
as it drives you not mad.
than start again.
That is the reason the forum exists.
enjoy
Well, I am not disputing what Toole's findings.
I am considering the factor of where the strongest reflected sound come from within the first 20ms and in my considerations I also included how much delay the reflected sounds come with. These factors are not described in your quote of Toole's findings.
I am simply speculating that we may need to include the directions and time delays of the reflected sounds into our analysis of the speaker and room interaction and our perception of sound reproduction.
As described in my earlier post (one or two pages back) that my U-frame speakers aim at not only flat on-axis frequency response but also the flatest possible power response.
For conventional monopole speakers, above baffle step, sound radiate into the front 2pi space and below the baffle step into 4pi space until it gradually hits the floor boundary. Therefore the power response is rather uneven.
For typical dipole speakers without a rear tweeter, obviously there is a power dip at higher frequencies. For dipole speakers with a rear tweeter, a dipole or U-frame bass would have mismatch with the higher frequencies because of the floor boundary.
My theoretical stuffed U-frame speakers would radiate into the front 2pi space above baffle step. Below baffle step it is similar to dipole therefore radiate 4.8dB less power, which brings it much closer to the power of 2pi space. The woofers are monopole therefore radiating into 2pi space. The design was exactly aiming at having the smoothest power response possible.
Nevertheless, what my earlier post said was to suggest that even with a smooth power response, I found the sound was less satisfying when comparing to the NaO dipole speakers I built, in terms of recreating the acoustic space simulating to live events.
So I looked deeper into the reflections. I did not stay at simply looking at the total acoustic power across the entire bandwidth. I started looking at the directions of the reflections and the time delays of the reflections in order to find an answer.
I am considering the factor of where the strongest reflected sound come from within the first 20ms and in my considerations I also included how much delay the reflected sounds come with. These factors are not described in your quote of Toole's findings.
I am simply speculating that we may need to include the directions and time delays of the reflected sounds into our analysis of the speaker and room interaction and our perception of sound reproduction.
As described in my earlier post (one or two pages back) that my U-frame speakers aim at not only flat on-axis frequency response but also the flatest possible power response.
For conventional monopole speakers, above baffle step, sound radiate into the front 2pi space and below the baffle step into 4pi space until it gradually hits the floor boundary. Therefore the power response is rather uneven.
For typical dipole speakers without a rear tweeter, obviously there is a power dip at higher frequencies. For dipole speakers with a rear tweeter, a dipole or U-frame bass would have mismatch with the higher frequencies because of the floor boundary.
My theoretical stuffed U-frame speakers would radiate into the front 2pi space above baffle step. Below baffle step it is similar to dipole therefore radiate 4.8dB less power, which brings it much closer to the power of 2pi space. The woofers are monopole therefore radiating into 2pi space. The design was exactly aiming at having the smoothest power response possible.
Nevertheless, what my earlier post said was to suggest that even with a smooth power response, I found the sound was less satisfying when comparing to the NaO dipole speakers I built, in terms of recreating the acoustic space simulating to live events.
So I looked deeper into the reflections. I did not stay at simply looking at the total acoustic power across the entire bandwidth. I started looking at the directions of the reflections and the time delays of the reflections in order to find an answer.
Having said that, I have to say that for dipole speakers I would like to have 1.5m distance from the front wall at the very minimum, and possibly 2m to be ideal. Even so the first reflection points in the front wall in my implementation are half damped.
Without 1.5m distance, the reflected sound would be less than 8ms and would mess up with the original direct sound.
I guess for those that can not place their speakers 1.5m - 2m from the wall they may have to forget about dipole speakers. Monopole speakers, and preferrably CD speakers, would work much better than dipole.
Without 1.5m distance, the reflected sound would be less than 8ms and would mess up with the original direct sound.
I guess for those that can not place their speakers 1.5m - 2m from the wall they may have to forget about dipole speakers. Monopole speakers, and preferrably CD speakers, would work much better than dipole.
Johnk,
It makes sense. I am still experimenting. I will compare both sealed and U-frame for the bass with the same drivers and cabinet. But first I will lower the XO point from 180Hz to 130-150Hz tonight to get it ready for comparison, as the U-frame woofer can not cross that high with the dipole peak and dip.
Regards,
Bill
It makes sense. I am still experimenting. I will compare both sealed and U-frame for the bass with the same drivers and cabinet. But first I will lower the XO point from 180Hz to 130-150Hz tonight to get it ready for comparison, as the U-frame woofer can not cross that high with the dipole peak and dip.
Regards,
Bill
The Toole book repeatedly shows how below about 200Hz (depending on the room), the frequency response gets very unpredictable, often in the overall direction of more bass. I'm not surprised that trying to predict power matching in that lower modal are didn't quite work.
Btw, I'll repeat that the Toole book was excellent, and I'm interested in the discussion that results from more people reading it.
Btw, I'll repeat that the Toole book was excellent, and I'm interested in the discussion that results from more people reading it.
That's the crux of the matter, it seems to me. I will get the Toole book, but it worries me that he apparently did not address this directly.
But, we shall see. I hope to be enlightened by the book, and I agree that the more of us read it the better we can discuss.
regines, I love your posts. I suspect I would prefer the same sound you do. I will look up the Unity's...it never ceases to amaze me the world-wide variety of components.
Best, Charlie
salas said:
According to Toole's book, this approach somehat flawed. Apart from limited SPL the only common flaw in low-fi speakers is a bass rolloff and in the rest of the frequency range they are all bad in their own ways. Checking a mix with a particular set of colored speakers and making slight adjustments based on that will make the mix better for only those and similarily colored speakers. All other equipment gets a worse mix.
You can't look at sound reproduction that way. It's the arrival time, level, direction and spectrum of the early first reflections that make the reproduction more or less accurate.
Knowing the directivity pattern of a particular speaker is more meaningful than knowing it's overall power output. But in the end the room/speaker system should have a frequency independend constant power output.
Best, Markus
Knowing the directivity pattern of a particular speaker is more meaningful than knowing it's overall power output. But in the end the room/speaker system should have a frequency independend constant power output.
Best, Markus
I have now tried the OB bass on my U-frame speakers.
Two SS26W8861T00 10" revelators have been housed in two separate stuffed, sealed enclosures of 35 liters each giving a Q of about 0.68 with a -3dB at around 50Hz. The sealed enclosures were designed with the right volume and depth and a removable back so that I could go OB if I wanted to. They are actively low passed at 180Hz with an acoustic BW3, confirmed by measurement. Below 50Hz the Peerless XLS 12" sealed subs were to take over the duty.
Because I found the bass quality was not as good as the NaO U-frame bass using a single XLS 12", two days ago, I opened the back of the enclosures.
I have to say I am not going back. I like the sound. The music is much cleaner, even though I have not tailored the active crossover to the U-frame response yet, so the response of the U-frame with the first dipole peak and U-frame 1/4 wave resonance were audible. Note that in my case the EQ of 6dB/oct dipole rolloff is unnecessary because I have a Fequal at 65Hz. Another surprise was that the woofers did not run into large excursions even at high SPL, so they don't need to be HPed. I am very happy with this finding.
This came as a bit of surprise, as I did not expect much difference at frequencies this low.
When hearing the bass alone, I could not detect if the OB bass was better than the sealed or not. They sounded similar. When combined with the upper U-frame playing music content, the difference was obvious.
I am guessing:
1. The OB back waves have reversed phase comparing to a sealed box, and it happens that in my room with my particular placement somehow it produces better polar response.
2. These drivers work better in OB (with air impedance identical in front of the driver and behind the driver) than sealed in a small enclosure (with high impedance behind the driver).
3. In the Phoenix subwoofer documents Linkwitz mentioned that the XLS 12" has better distortion figures when working in OB than sealed and he published some measurements / graphs to support this. I guess the same applies to the SS 10".
4. It is possible that my cabinet does not have the best bracing and a seal box makes the box resonate more.
Or anything else? Psychological prejudice?
Regards,
Bill
Two SS26W8861T00 10" revelators have been housed in two separate stuffed, sealed enclosures of 35 liters each giving a Q of about 0.68 with a -3dB at around 50Hz. The sealed enclosures were designed with the right volume and depth and a removable back so that I could go OB if I wanted to. They are actively low passed at 180Hz with an acoustic BW3, confirmed by measurement. Below 50Hz the Peerless XLS 12" sealed subs were to take over the duty.
Because I found the bass quality was not as good as the NaO U-frame bass using a single XLS 12", two days ago, I opened the back of the enclosures.
I have to say I am not going back. I like the sound. The music is much cleaner, even though I have not tailored the active crossover to the U-frame response yet, so the response of the U-frame with the first dipole peak and U-frame 1/4 wave resonance were audible. Note that in my case the EQ of 6dB/oct dipole rolloff is unnecessary because I have a Fequal at 65Hz. Another surprise was that the woofers did not run into large excursions even at high SPL, so they don't need to be HPed. I am very happy with this finding.
This came as a bit of surprise, as I did not expect much difference at frequencies this low.
When hearing the bass alone, I could not detect if the OB bass was better than the sealed or not. They sounded similar. When combined with the upper U-frame playing music content, the difference was obvious.
I am guessing:
1. The OB back waves have reversed phase comparing to a sealed box, and it happens that in my room with my particular placement somehow it produces better polar response.
2. These drivers work better in OB (with air impedance identical in front of the driver and behind the driver) than sealed in a small enclosure (with high impedance behind the driver).
3. In the Phoenix subwoofer documents Linkwitz mentioned that the XLS 12" has better distortion figures when working in OB than sealed and he published some measurements / graphs to support this. I guess the same applies to the SS 10".
4. It is possible that my cabinet does not have the best bracing and a seal box makes the box resonate more.
Or anything else? Psychological prejudice?
Regards,
Bill
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